- 8 September 2005 -

Quantum calculations of H2O and LiH

Researchers at the Department of Energy's Lawrence Berkeley National Laboratory and the University of California at Berkeley have simulated the process by which a quantum computer could calculate to high precision an important basic property of two small molecules. Simulated quantum
calculations of the ground-state energies of water(H2O) and
lithium hydride (LiH) are the first of this kind ever done for specific molecules.

The total electron charge density (shown in green) of a quantum dot of gallium arsenide, containing just 465 atoms. (Image: Lin-Wang Wang)

Alán Aspuru-Guzik, Anthony Dutoi, Peter Love, and Martin Head-Gordon report on their work in the the journal Science. Head-Gordon is a staff scientist in Berkeley Lab's Chemical Sciences division and UC Berkeley professor of chemistry; Aspuru-Guzik is a postdoctoral fellow and Dutoi a graduate student in the Head-Gordon group. Love is a senior applications scientist on the staff of D Wave Systems Inc in Vancouver, BC.

The researchers developed a quantum-computational algorithm and ran it on a classical computer to demonstrate that quantum computers comprised of only tens or a few hundreds of quantum bits (qubits) could calculate significant information about real molecular systems to high accuracy.

Thus a relatively small quantum computer could surpass the most powerful quantum-chemistry calculations possible with today's classical supercomputers.

"What we have done is demonstrate - by using a quantum algorithm to
determine the states of minimum energy for two real molecules that
quantum computing can deliver on the promise of giving highly accurate practical solutions to interesting chemical problems," says Aspuru-Guzik.

Source:http://www.lbl.gov